Display screen or portion thereof with a graphical user interface



FIG. 1 depicts a front view of a display screen or portion thereof with a graphical user interface according to a first embodiment.

FIG. 2 depicts a front view of a display screen or portion thereof with a graphical user interface according to a second embodiment; and,

FIG. 3 depicts a front view of a display screen or portion thereof with a graphical user interface according to a third embodiment.

The outermost broken line rectangle illustrates a display screen or portion thereof and forms no part of the claimed design. The remaining broken lines illustrate portions of the graphical user interface and form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with a graphical user interface, as shown and described. 